Faulty design!
Returning our box-1) Even size 5 for our beagle (recommended 4 for breed) couldn't pass for int'l travel coz of the stupid, faulty design of the box itself! The height inside is greatly reduced due to the deep boxes constructed right in the middle on the top. 2) If you want to use the box by itself without the wheels, the mindless base design like a curve keeps it rocking back and forth with the shift of the dog's weight. My dog got scared of entering inside! 3) Feels cheaper quality than others